The Collaborative International Dictionary of English v.0.48:

Fore-topmast \Fore`-top"mast\, n. (Naut.)
   The mast erected at the head of the foremast, and at the head
   of which stands the fore-topgallant mast; the mast next above
   the foremast. See Ship.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fore-topmast
    n 1: the topmast next above the foremast